#include <iostream>
#include <algorithm>
using namespace std;
bool check(int a,int b,int c)
{
    int tmp[]={a,b,c};
    sort(tmp,tmp+3);
    return (tmp[0]+tmp[1]>tmp[2]);
}
int main()
{
    int n;
    cin >> n;
    if (n>=45)
    cout << "YES";
    else
    {
        int arr[n];
        for (int i=0;i<n;i++)
        cin >> arr[i];
        for (int i=0;i<n;i++)
        {
            for (int x=i+1;x<n;x++)
            {
                for (int j=x+1;j<n;j++)
                {
                    if (check(arr[i],arr[x],arr[j]))
                    {
                        cout << "YES";
                        return 0;
                    }
                }
            }
        }
        cout << "NO";
    }
}